Hypernym for "clients", "members" and "partners"
Solution 1:
Stakeholders would be the term.
Stakeholders : A person, group or organization that has interest or concern in an organization. Some examples of key stakeholders are creditors, directors, employees, government (and its agencies), owners (shareholders), suppliers, unions, and the community from which the business draws its resources.
Solution 2:
You might try stakeholders:-
- (Economics, Accounting & Finance / Banking & Finance) a person or group owning a significant percentage of a company's shares
- (Business / Industrial Relations & HR Terms) a person or group not owning shares in an enterprise but affected by or having an interest in its operations, such as the employees, customers, local community, etc.
Solution 3:
Less sophisticated than "stakeholders" is associates.
Associate: person joined with another or others in an enterprise, business, etc.; partner; colleague.