Pull data from WP-CLIENT custom fields into Gravity Forms dropdown

Thanks, I am thinking I may need to hire someone to do this but perhaps it’s easier than I think. I have a client we are using wp-client plugin to manage their users, each user has several custom account numbers using the custom fields in wp-client (1-10 account numbers). So I need a simple form that when logged in pulls the clients account numbers into a drop down field. I know I need to use Gravity Forms pre_render but I am not sure how to pull the custom fields into the form. I appreciate any help.