You should not be specifying the access-address if you have multiple ENIs for performance purpose.
Not all clients are tuned to handle multiple IPs of a same node. Java client definitely does. If you are using java, you are good to go.
To exploit all the ENIs of cluster, you need to have a small hack in the client application. Lets say you have 3 boxes A, B, C with each one having 4 nics like A1, A2, A3, A4. and so on. What you should do is to specify different nics in the seed list of each client instances. i.e for client instance one give seed list as (A1, B1, C1) and for second client instance give (A2, B2, C2).
Note that this hack is needed only when you have mutliple nics and for perf reasons. If its not for perf reasons, you can simply give A1 as seed IP for all client instances and they will discover the rest of the cluster. It may not use all the NICs in this case.