Klein enlisted in the US Army in 1951 where he served as a clerk typist on Governors Island, New York. After military service, and with the assistance of the G.I. Bill, Klein majored in accounting at Upsala College, graduating in June 1957, and was hired by a Manhattan accounting firm, Joseph Fenton and Company. He was assigned to assist Joe Fenton in an audit of a music publishers' organization, the Harry Fox Agency, and several record companies, including Dot Records, Liberty Records, and Monarch Records. In an early setback to Klein's career, he was fired by Joseph Fenton and Company after four months because of chronic lateness. The company wrote to the State of New Jersey urging officials not to approve him as a Certified Public Accountant, and Klein chose not to take the examination. He briefly attended law school but soon dropped out.