Smarty templates are HTML files. ok, they are a little bit more complex 'cause of the loops, ifs and so on.
What do you mean with client? The designer creating your layout?
Maybe you can get them lern a little bit, a professional designer will do this for you.
Or you could even seperate the layout from the logical-templates.
so you woul have a
main.tpl -> there is the loop, in this loop you include the
main.layout.tpl -> in which the table-row or whatever is saved.
so your designers just have to edit the row defined in main.layout.tpl, and dont need to do anything with the loop.
but this is very circular.