Disclaimer: I'm not a lawyer, I've never played one on TV, and it has been ages since I've stayed at a Holiday Inn.
However, it sounds like you've stated clearly that your need is a lawyer who SPECIALIZES in contract law, with EXPERIENCE doing so for Digital Agencies.
A great way to find someone like that is to ask other agencies that you have a good relationship with.
For critical professional services like legal representation, I've always had a strong preference for a referral. Preferably from someone I know who has enough similarity in business and principles that I can reasonably expect to have the same good outcomes they've enjoyed.
I'd say this is a matter of asking a few friends in the business for referrals - and then interviewing them.
If you don't have friends in the business - consider searching Clarity for people with digital agency experience (rather than legal experience), and request a call to get their recommendations on counsel.