Is there any way i can access the object of one client session from another client session?
Unless you have isolated your Entities to the client Session (ClassDescriptor.setIsIsolated) then the ClientSession does not actually hold any entity instances. So unless you have caching disabled all queries against a ClientSession will return the same entity instances.
If you have isolated Entities or are actually using a UnitOfWork then you will have to get the value from the holding UnitOfWork/IsolatedClientSession. It is not advisable to access a UnitOfWork or ClientSession concurrently with multiple threads.