I also tried to fix this on my install, but to no avail. Instead, I simply added this to the .htaccess file at the root of the domain:
Options +FollowSymlinks -MultiViews
RewriteEngine On
RewriteBase /
RewriteRule ^client/(.*) https://example.com/BLESTA-SUBDIR/client/$1 [R=301,NC,L]
Hope this helps.