The successful deployment of LTE heterogeneous networks (HetNets) depends crucially on the inter-cell interference (ICI) management. Among ICI coordination schemes, fractional frequency reuse (FFR) is considered as an efficient technique well-suited to OFDMA-based HetNets. Two coupled questions in this context are: 1) how to associate users to appropriate base-stations considering the long list of available candidate cells, and 2) how to allocate frequency resources among multiple cells. In this paper, we treat the multi-cell frequency allocation as frequency partitioning among multiple reuse patterns, and develop a novel algorithm to solve these two coupled questions in a joint manner. We also provide practical criterion to select the set of essential candidate patterns from all possible patterns. Results show that the proposed joint strategy improves both the cell-edge user and overall network throughput.