arahmanov,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script>
$(function(){
var client = $('#pnlClientDetails td:contains("Ф.И.О")+').text();
alert(client);
})
</script>
</head>
<body>
<table id="pnlClientDetails"><tr>
<td class="CDataHeader" style="width:100px;">Ф.И.О</td>
<td class="CDataContent" style="white-space: nowrap;">Иван Иванович</td>
</tr></table>
</body>
</html>