Should you wish to view the clients fps then you can open the 'FPS Monitor' by pressing the 'Ctrl + F' keys by default.
As well as your fps the monitor will also display what DirectX(dx) version the client is using.
You can collect statistics relating to your fps by clicking on the 'Start Collecting Stats' button.
Once you click on the 'Stop Collecting Stats' button your results will be copied to your clipboard.
They can then be pasted into any suitable application.
By clicking on the check box in the lower right of the monitor, once you stop collecting statistics a window will appear with a summary of your 'Mean FPS:' and 'Mean Frametime' during the recorded session.
Should you feel that your fps output is low then you may wish to consider lowing the clients graphics settings, which can be found in the 'Display and Graphics' tab of the game menu that is accessible by pressing the ESC key.