Margetic's professional career began in 1978 for Club Atletico San Telmo from the Isla Maciel district of Avellaneda.

He came to the United States to play for the Detroit Express in 1979 and then moved on to the Chicago Sting in 1981, where he went on to win NASL Soccer Bowls in 1981 and 1984.

Margetic played in 130 NASL games, scoring 42 goals and 59 assists for 143 points, which ranks him 34th all-time in the league.

Margetic scored the last goal in the history of the NASL in the 82nd minute of game two of the 1984 Soccer Bowl series.

After the end of the NASL, Margetic played six seasons in the Major Indoor Soccer League for the Chicago Sting, Kansas City Comets, Cleveland Crunch and Tacoma Stars, and nine seasons in the National Professional Soccer League for the Chicago Power and Detroit Rockers.