Animated Search Form icon to button - search

Question

I'm trying to use this Search Form code but I want to make it so that on Click the magnifying glass icon switches to a Search button. I haven't been able to figure it out. Any ideas?
https://codepen.io/CBeghin/pen/HeuiF
<div id="wrap">
<form action="" autocomplete="on">
<input id="search" name="search" type="text" placeholder="What're we looking for ?"><input id="search_submit" value="Rechercher" type="submit">
</form>
</div>
#import url(http://fonts.googleapis.com/css?family=Lato:100,300,400,700);
#import url(https://raw.github.com/FortAwesome/Font-Awesome/master/docs/assets/css/font-awesome.min.css);
body {
background: #DDD;
font-size: 15px;
}
#wrap {
margin: 50px 100px;
display: inline-block;
position: relative;
height: 60px;
float: right;
padding: 0;
position: relative;
}
input[type="text"] {
height: 60px;
font-size: 55px;
display: inline-block;
font-family: "Lato";
font-weight: 100;
border: none;
outline: none;
color: #555;
padding: 3px;
padding-right: 60px;
width: 0px;
position: absolute;
top: 0;
right: 0;
background: none;
z-index: 3;
transition: width .4s cubic-bezier(0.000, 0.795, 0.000, 1.000);
cursor: pointer;
}
input[type="text"]:focus:hover {
border-bottom: 1px solid #BBB;
}
input[type="text"]:focus {
width: 700px;
z-index: 1;
border-bottom: 1px solid #BBB;
cursor: text;
}
input[type="submit"] {
height: 67px;
width: 63px;
display: inline-block;
color:red;
float: right;
background: url(data:image/png;base64,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) center center no-repeat;
text-indent: -10000px;
border: none;
position: absolute;
top: 0;
right: 0;
z-index: 2;
cursor: pointer;
opacity: 0.4;
cursor: pointer;
transition: opacity .4s ease;
}
input[type="submit"]:hover {
opacity: 0.8;
}