aratype I am asking about doing search when you click on the "magnifying glass" not other thing!
If the "magnifying glass" has no role why putting it!
If you wished to have the search icon to be clickable, You can perform the following steps:
1) Configure the specific module to show search button as suggested by Paul
2) Copy the search icon i.e. templates/ja_megastore/images/search.png to /images/stories/virtuemart folder
3) Thereon, You can upload the above image in module configuration option i.e. MOD_VIRTUEMART_SEARCH_BUTTON_IMG
4) Try add this to custom.css file :
.head-search .search input {padding: initial;}
.head-search .search .button {position: absolute;top: 50%;height: 30px;right: 10px;border: 0 none;width:30px;top: 50%;transform: translateY(-50%);-webkit-transform: translateY(-50%);}
.head-search .search::before{background:none !important;}
You will have the search icon functioning as button as seen in screenshot in similar position appearing alike the background image as seen in default template.