We had a client like this. I was glad he fired us because at the time I really didn't know better than to allow things to drag on and on even as they were leading to total disaster.

What will kill you here is if you don't have an iron clad scope of work, and if you don't setup your client's expectations PERFECTLY. They will always be so in their heads about ideas they won't remember what you talked about, they'll want you to do job B when you show up to do job A, and unless you read their minds they probably won't be happy at the end. You will ALWAYS chase a moving target with these kinds of jobs.

After some lessons learned, we now only take clients with the mental fortitude to decide they want something and stand by it, not try to outplay us at our own game, or on the flip side be so indecisive as to not know what they want nor communicate to us clearly what their expectations are.

We only ever had success with one such client early on - we did a thorough prewire with patch panel trimout on everything, popped some speakers in the ceiling, TVs on the wall, and called it a day. He took it from there as far as "the system" was concerned. We put the framework into place and then he was able to geek out to his heart's content with the equipment of his choice.

Oh, and have your change order form ready. You'll probably be writing a few of them.