In this study, the problem of optimum subcarrier allocation in different numbers to users in OFDMA systems is discussed. OFDMA systems can be modelled by random bipartite graphs in scope of graph theory. Optimum subcarrier allocation with fixed numbers can be done by using maximum matching algorithms with providing fairness between users. In this study, Multi-(REHK)-E-2 algoritm which provides subcarrier allocation in different numbers is proposed in accordance with requirements of different users. The results obtained with proposed algorithm shows that optimum subcarrier allocation according to user needs can be done by sacrificing some amount of performance. Besides, maximum frequency diversity and fairness between users also are provided.