As the CEO of digital agency Vuzum but also the founder of our own startup Widgetic, I can tell you that we've got a lot of similar requests. But we turned them down, and always will.
The reason is simple: if we want to invest time into an idea, we'll invest in our own. And we'll get 100% of the equity while we're doing it.
And more than that, starting a product with someone involved as a partner, who is miles away, would happen with a lot of legal issues and mistrust.
If you're going this route to get an MVP out it's also a bad decision, because if - by the smallest chance - is going to be successful, this initial partnership will follow you across your product's lifetime. See how Facebook paid 60M to the twin brothers for similar reasons.