I'm looking for a one-word noun to describe someone who posts a project idea for a freelancer to pick up. They describe the project and project need, but they are not the producer. For example, "I'm in need of a logo for my business. I'm the "?", and the person who will design the logo is the producer."
I believe sponsor is the word used, in the corporate world at least
In my experience as a designer, that person is in the vast majority of cases referred to as the 'client'. In some in-house scenarios I have seen them called the 'originator' of the project.
In television parlance, you are the creator of the show, and may carry over to projects in general.