When using EF 4, MM 4, VS2010 and the following LINQ query in MM biz tier,

 IQueryable<ClientEntity> query = from o in this.ObjectContext.ClientEntities
                                                             select o;
            return this.GetEntityList(query);

what is the syntax to bring back a subset of fields,
select new {o.FirstName, o.LastName}; doesn't work; however, the foreach analysis does, but that is not what I want to return.
It gives me an error that I am trying to implicitly cast an anonymous type to my 'MM entity' type and implies that there is a specific cast for this, I don't know what this would be. I really don't want to bring back a large number of fields when I only need a few. Maybe I have to build a separate EF class for just this purpose but it seems like a waste. I couldn't find anything on this in the MM Guide.
Thanks for any help!