.htaccess to hide extension for both html and php files - php

Question

I'm working on some PHP pages for a client and I run into a problem.
He likes links for his website to be http://www.website.com/about (without the extension). In his .htaccess is this code:
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.website.com/$1 [R,L]
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html
</IfModule>
Now, the pages i'm making are having extension of php and there is my problem. I have tried several different variations of .htaccess and nothing seems to work. If there is contact.html the URL will be /contact, but if i rename that contact.html page to contact.php and i open /contact page again it is showing me 404 page.
I tried several .htaccess and they are:
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^(.*)$ $1.html [L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.*)$ $1.php [L]
RewriteCond %{REQUEST_URI} \.((html)|(php))$
RewriteRule ^(.*)\.([^.]+)$ $1 [R,L]
another one:
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.website.com/$1 [R,L]
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
</IfModule>
I tried more, but they are all gone now. Basically, nothing is working and I don't know what the problem is.
Any help would be awesome...