The short answer is yes. However I wouldn't recommend doing it. Instead I would just pass the query itself as a string and create the SQLCommand in the service.
This question explains how to pass an object from a client app to a WCF service; How to pass Client Objects to WCF Service
Basically if you create the SQLCommand object client side you're; 1) allocating/initializing an object 2) having that object serialized and deserialized into an equivalent object in the service.
If you pass it a string you're instead; 1) allocating/initializing a string 2) passing it to the service which allocates and initializes a SQLCommand object.
The latter is simpler and more efficient.