Are the two tables connected in your database at all? If not, you likely have to redesign your database slightly. Typically, an Orders table would have a ClientId of some sort, which is a primary key of the Clients table and a foreign key in the Orders table. If you did that, then you could pull the Clients data from the Client table and the relevant Orders using something like:
foreach(Client c in context.Clients)
Best of luck!