<input type="search" class="placepicker form-control" id="s" name="#s" data-map-container-id="collapseOne" placeholder="Lombok">
function transform(){ var inp = $('#searchform #s'); inp.val(inp.val().split(/tours[^\=]*=/).join('tours&s=')); }
<input type="submit" id="searchsubmit" onclick="transform();" value="Поиск" />