A group of joyful A-listers joined former President Clinton yesterday for a Hamptons birthday bash. Among the glitterati said to be on the guest list for Clinton’s 64th birthday party were designer Vera Wang, who created his daughter’s wedding gown, Katie Couric and music icons Paul McCartney and Jimmy Buffett. The party was held at the Water Mill home of his longtime aide Doug Band and his wife, Lily, and catered by Jason Weiner of Almond restaurant in Bridgehampton. Clinton’s wife, Secretary of State Hillary Rodham Clinton, co-hosted the party that was also set to include model Christie Brinkley, “Today Show” host Matt Lauer and Goldman Sachs CEO Lloyd Blankfein. Clinton’s birthday was Thursday, and McCartney made it fab for the ex-prez by calling and serenading him with The Beatles’ 1967 hit “When I’m Sixty-Four.”