RewriteEngine On

# Always rewrite tmp file access
RewriteRule ^(tmp/.*)$ index.php?REQUESTED_URL=$1 [L,QSA]

# If the request is not for a valid file
RewriteCond %{REQUEST_FILENAME} !-f
# If the request is not for a valid link
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(.*)$ index.php?REQUESTED_URL=$1 [L,QSA]