Change the line as follows
Execute-Process -FilePath "$dirFiles\Oracle\client\setup.exe" -Arguments "-silent -waitforcompletion -nowait -responsefile '"$dirSupportFiles\oracle\client_admin.rsp'"
Should work
Dan"
Execute-Process -FilePath "$dirFiles\Oracle\client\setup.exe" -Arguments "-silent -waitforcompletion -nowait -responsefile '"$dirSupportFiles\oracle\client_admin.rsp'"
Should work
Dan"