Not enough info to give specifics.
Anyways, this is for a client, aren't you getting paid to know how to tackle this stuff? I mean, you wouldn't have taken on the job if you (or your company) didn't know how to do this, right?
Problems like this require experience and creativitity. Both of which don't normally come cheap. I think I have the answers, but they're not worth giving away for free.
You might try rephrasing your question(s) to be a lot more specific.