“When I write my memoirs, which will be, of course, in verse, on the subject of you and how awful you are, I will be infinitely terse,” the Magnetic Fields’ Stephin Merritt sings in the wryly titled “Life Ain’t All Bad,” expounding on his mother’s thieving ex-boyfriend, who vandalized the family car and killed Merritt’s dog.

“Yeah, he was a piece of work,” Merritt confirms from Atlanta of his now-dead nemesis in that slice from 50 Song Memoir, the singer/songwriter’s magnificent new opus with the Magnetic Fields that chronicles his first 50 years of life. Or as he puts it in that song’s terse kicker: “I hope I never run into another piece of shit like you.”

The idea for a five-disc autobiographical album came from Robert Hurwitz, then head of the Magnetic Fields’ record label Nonesuch, after Merritt had finished writing documentary music for This American Life.

“I had been doing completely truthful lyrics, which is a new thing to me—there’s no reason to be completely truthful and many good reasons not to be,” Merritt, 52, says on the road to his band’s April 14-15 shows at the Berklee Performance Center. “[The idea] appealed to me as something that I had not done before.”

It’s not that he hadn’t tackled a mammoth concept album before: The Magnetic Fields’ 1999 breakthrough, 69 Love Songs, took a similar format and bridged cabaret, country and synth-pop.

But the prolific songwriter sought an even broader palette for 50 Song Memoir, released March 10. He enlisted a dozen musicians and singers (cored by longtime bandmates Claudia Gonson, Sam Davol and John Woo) while personally playing more than 100 instruments, from keyboards and drum machines to guitars, basses, ukuleles and a menagerie of percussion items.

To enforce variety, Merritt set some rules: He’d use each instrument on only seven songs, none of those songs would abut, and he wouldn’t pair the same instruments on more than one song. “In the ’80s, we all said, ‘My gender is none of your business unless you’re going to sleep with me,’ and in the Magnetic Fields, we say, ‘What instrument you’re hearing is none of your business.’ ”

So tracks range from the opening ukulele ditty “Wonder Where I’m From” (with Merritt mulling a birth courtesy of “barefoot beatniks”) to the disco sashay of “Hustle ’76,” the quirky psychedelia of “The 1989 Musical Marching Zoo” (named for members of a ’60s bubblegum supergroup who wore animal heads), the dark throb of “How to Play the Synthesizer” and the bubbly electro-pop of “Danceteria!”

“Maybe I got my love of musical eclecticism from Danceteria,” Merritt says of the New York club he frequented in the ’80s. “More likely I got my love of Danceteria from my musical eclecticism.”

He credits the influence of Boston college stations WZBC and WHRB, having lived in the area from 1974 to 1993. Merritt recalls living in “33 houses in 23 years” with his mother, who lent memories for the album—and clearance for songs about her. The same didn’t go for his father, who Merritt met twice in his life (the second time after starting the year-and-a-half album project) and who earned the somber “Fathers in the Clouds.”

“He noticed that I called him a ‘no-goodnik dad,’ but I put [the words] in my mother’s mouth, so it’s not quite as bad as it could be,” says Merritt, who turns his lyrical lens to everything from his ex-boyfriends and medical afflictions to the book Ethan Frome. Songs led by “I’m Sad!” represent a mid-’90s period of what he admits was “clinical depression.” But things look up before the closing “Somebody’s Fetish,” where Merritt ends, “And I, who have wandered alone for so long, on my little island, just like King Kong, here at the end, I have written a song… for you.”

And he’ll address listeners in concert from the shell of a giant dollhouse (evoking the tin ones he collects), centering a Magnetic Fields septet and playing all 50 of the album’s songs—split between two nights—without any other old favorites.

As the deep-voiced Merritt intones with certainty, “Fifty is enough.”

The Magnetic Fields play the Berklee Performance Center on April 14-15.