With Vundle simply add this to your .vimrc:
Plugin 'vmchale/tokei-vim'
Of couse, you'll need to install tokei as well.
Because it runs tokei in your current working directory, you're probably going to want a plugin to change the root directory appropriately. I use vim-rooter.
By default, tokei-vim provides a command and a keybinding:
:Tokei
<silent> co
Press q to exit when it displays the code content of your project.
You can also set g:tokei_exlude to exlude a file or pattern; tokei follows the as a .gitignore. If you wish to exclude two patterns, separate them with a comma with no spaces, e.g.
let g:tokei_exclude=TODO.md,README.md