Nginx:
location / { if (!-e $request_filename){ rewrite ^(.*)$ /index.php?s=$1 last; break; } }
Apache:
<IfModule mod_rewrite.c> RewriteEngine on RewriteBase / RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.*)$ index.php?s=/$1 [QSA,PT,L] </IfModule>