You have the control which fields to show for users from which client category and which seller category. For this to work you need to assign your custom profile field in the desired client or seller category.
You don't need to touch any code for this.
- Go to Sellacious backoffice. Select Categories > Client or Categories > Seller as you want.
- Create or edit a user category.
- Choose the tab "Profile Fields"
- Select the custom fields that should be shown for the users of this category
Now you can see that any user in this client/seller category will have this field in their profile.
Hope this helps. Please let us know if you need further clarification.