I’d say that your Redirect statement is correct so I don’t know why the %{REQUEST_URI} string was passed, too.
When all else fails, I fall back on mod_rewrite. This should settle the trick for you:
# .htaccess in DocumentRoot of old website
RewriteEngine on
RewriteRule .? http://newsite.com/ [R=301,L]
IF the two domains share the same DocumentRoot (the new one parked on the old one),
# .htaccess in DocumentRoot of old website
RewriteEngine on
RewriteCond %{HTTP_HOST} oldsite[COLOR="#A9A9A9"]\\.com[/COLOR] [NC]
# the \\.com isn't required if oldsite domain name is not contained in the newsite domain name
RewriteRule .? http://newsite.com/ [R=301,L]