You have included the Q_OBJECT macro in the declaration of class ClientRunnable, but the base class QRunnable is not derived from QObject. Therefore, all of the meta-object boilerplate that the Q_OBJECT macro inserts (and which the moc compiler looks for) can't be compiled because the required QObject base class code to support it isn't there.
If you need support for signals and slots in ClientRunnable (I don't see that you do), then you can derive it from both QObject and QRunnable. If you don't, then remove the Q_OBJECT macro, delete the moc_ClientRunnable.* files, and re-run qmake (if you are using Qt Creator) or a rebuild all if you are using Visual Studio.
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