Two places to look:
1 - advertise it as a job on Linked In. Yes, I did say a "job". There are real people looking for work who could become partners. I'd suggest you start by hiring and offer the partnership as a performance bonus. That's pretty motivating for a sales/biz dev person
2 - ask your clients if they can introduce you to someone. These folks know, like and trust you and your brand and a private approach from you will carry real weight. They'll be flattered to be asked and you may be surprised who comes out of the woodwork.

Good luck