given that you're using a fairly old FortiClient version, I'm not sure if the registry settings can be retained, and deploying a FortiClient installation from scratch with a configuration file requires a modified installation file, which in turn relies on EMS.
However, you can technically just do a regular FortiClient installation, and prepare a config backup (.xml file), and then restore that config file to the installed FortiClient(s).
I'm really not sure if this can be done in bulk though, or if a prepared FortiClient configuration backup would need to be restored individually on each client; any guides we have for bulk deployment/configuration/upgrade of FortiClient usually relies on EMS.
+++ Divide by Cucumber Error. Please Reinstall Universe and Reboot +++