What happens when non-partners bring in new clients?

I'm curious how various firms deal with the issue of non-partner employees bringing in business. I'm a non-partner employee at a small firm, and for the first time I have some serious prospects in the pipeline. But I'm not sure how to raise the issue with my boss, considering we have no explicit policy about this topic, no profit-sharing program, zip, zilch, nada. If I land a substantial new client, do I get a taste of the profits, or just a nice performance review and a few extra basis points in my annual increase/bonus? If I bring in several new clients, and I get tired of making my boss richer and decide to go out on my own, can I bring "my book of business" with me? This is not in any employee handbook. I'm an at-will employee and haven't signed anything related to this subject.