Klein graduated from the Hackley School and the University of Pennsylvania with a degree in American civilization. In 1969 Klein began reporting for the Essex County Newspapers, and "The Peabody Times" in Peabody, Massachusetts. In 1972 he reported for Boston's WGBH, and until 1974 he was also the news editor for "The Real Paper" in Cambridge, Massachusetts. He was a contributing editor for "Rolling Stone" from 1975 to 1980, and Washington bureau chief from 1975 to 1977. He became friends with actor–director Tom Laughlin after interviewing him for "Rolling Stone" and appeared briefly as a reporter in Laughlin's 1977 film "Billy Jack Goes to Washington".