This script can be used to send an arbitrary string to the terminal clipboard using the OSC 52 escape sequence, as specified in http://invisible-island.net/xterm/ctlseqs/ctlseqs.html, section "Operating System Controls", Ps => 52.
Plug 'kuntau/vim-osc52'
Edit your .vimrc
to include this code
vmap <C-c> <Plug>(YankOSC52)
This will map Ctrl+C to copy. You can now select text in vim using the visual mark mode or the mouse, and press Ctrl+C to copy it to the clipboard.