Hi Raju,
Studio and Client are independent of each other. You do not need to install client before installing Studio.
May be you can try uninstalling first (which may not work), deleting the directories and files and then try the installation.
Worst case would be registry entries cleanup, but it should be that difficult.
Frankly, I never faced any issue with HANA Studio / client install. There were some issues with the parameter setting resulting into Java related errors, but that is a different issue which appears when you launch the studio.
Regards,
Ravi