Have you done a fresh install from the chronicles site.
Missing client files means you are missing files ie the game has not installed fully.
Take a screenshot of what's inside your mir chronicles folder. Also what size is the folder
In short, delete what you have done.
Download the installer from the main site, run the exe as admin.
Download the latest patch program. Unrar it and add it to your mir chronicles folder.
Run the patch program as admin.
Ensure you anti virus is not deleting mir.exe
BH