Born in Baltimore, Maryland, he graduated from Baltimore Polytechnic Institute. During his playing career, Klein was a minor league first baseman in the Washington Senators farm system from 1962 to 1968. A left-handed batter and thrower, he hit.278 in 1,733 at bats. After retiring from the field, he spent 16 years as a minor league manager and front office executive with the franchise, beginning in 1969 when it was still the expansion edition of the Senators, and continuing after it became the Texas Rangers in 1972. He managed farm clubs in the Class A Western Carolinas League and Carolina League, the Double-AEastern League and the Rookie-level Gulf Coast League between 1969 and 1978. In 1976, Klein also added the title of assistant farm system director of the Rangers, and was promoted to head of the club's farm system and then director, player procurement and development, between 1978 and 1982.
In October 1982, he was promoted to general manager of the Rangers, who had finished next-to-last in the American League West Division that season. The Rangers improved by 13 games to finish third in the AL West in 1983, but the team regressed to only 69 wins in 1984 and Klein was fired. He then joined the Kansas City Royals as assistant general manager for 1985, working with John Schuerholz during the Royals' first world championship season. In 1986, Klein received his second GM opportunity when he took over the front office of the Cleveland Indians. The '85 Indians had lost 102 games and finished last in the AL East, but, buoyed by the slugging of Joe Carter and Cory Snyder, Cleveland won 84 games in 1986—a 24-game improvement—and compiled its first winning campaign since strike-shortened 1981. The Indians were seen as a dark-horse contender for the AL East title in 1987, but instead they collapsed completely, losing 101 games and falling into the division basement. The front office was overhauled, and Klein was demoted. He eventually rejoined the Royals, this time as vice president of player personnel, in 1990–91. In 1992, he moved on to the Detroit Tigers, who were in a period of transition with former University of Michigan footballhead coachBo Schembechler serving as the team president. Klein was hired as the Tigers' scouting director, but moved into the general manager position at the end of the 1993 season. He ran the Detroit front office for two losing seasons, 1994 and 1995, which were also the last two clubs of the Sparky Anderson era, until another front office housecleaning cost him his job.
In his later life, Klein was an important figure in independent baseball. As executive director of the Atlantic League, Klein was in charge of day-to-day baseball operations for the organization. In August 2007, he returned to the public eye when he was called upon to discipline former MLB infielderJosé Offerman after a bat-swinging episode in Bridgeport, Connecticut. Klein was associated with the Atlantic League from its founding until his death on August 23, 2017, at Temple University Hospital in Philadelphia from complications from quadruple bypass surgery, only one day after his 75th birthday.
