How to change labels in the projects page

​I want to change labels in this page ex: Client -> Owner What is the file name where I can change these labels from?

screenshot:

https://snag.gy/75oUTb.jpg

I tried to do it by javascript, but it caused effect on all website pages, on previewing, editing or updating, the page turns to white.

This is my piece of code

echo "script type='text/javascript'
            window.onload = replaceTxt; 
             function replaceTxt() {
             var vr1 = document.getElementById('_bunch_bunch_projects_settings[client]').childNodes[1].childNodes[1].innerHTML;

             var vr11 = vr1.replace('Client','Owner');
}
             /script";