That's a hell of an ask there dude, especially for free!
Before trying to solicit it's probably best that you develop your story a bit more, save some money to pay an artist for their work, and make a body of work (in your case some comic scripts coupled with basic storyboards would probably work best) to show potential artists that you're serious and know what you're doing.
Also, you might wanna think about starting with a slower work rate. If you take a look around the western webcomic scene you'll realize that the average page rate is about 1-3 per-week. There simply aren't that many people in the western comic market who can meet the chapter-per-week page rate you're looking for with the style you're going for. And among the few who could many are working for Webtoons already and the rest almost certainly wouldn't work for free.
Not trying to discourage you, but I think you're severely underestimating the task here.
There's a writter on Tapas named Merryweathery who is pretty well known for making quite a number of stories with the help of commissioned artists. He wrote a guide on seeking artists that may be of use to you, so I'll leave it here:
http://forums.tapastic.com/t/how-to-find-an-artist-for-your-manga-comic-script/1828?u=zpreader