What should i look for in picking the best technical co founder to partner with?
You already have a partner, why would you complicate things with a third co-founder? Adding co-founders exponentially complicates decision-making and becomes increasingly more difficult to ensure that you're on the same page.
Just hire your technical staff/person as an employee. If the reason you're saying "founder" is because you can't pay an employee, that's a separate financial problem to address that should not be connected with the plan to find a co-founder.
As with any technical hire, you want someone who is a fit for your culture (the way people work together and how they solve problems together). Technical skills are somewhat interchangeable, but personality and work style are not.
I feel part of the answer that Paul has correctly stated below should include: "...So, you made a clickable prototype, but did you test the prototype with actual users and iterate with their feedback? If testing is complete and the UI and solution is solid, then find out if users would benefit and/or would pay for the solution. At that point, you could realistically proceed with hiring developers. Until then, it really doesn't matter what the prototype looks like.
What have you done to validate your market so far?