Help with a search box

Hello all, I hope someone can help me out here.

I am trying to improve a search box on a website, at the moment you can search by keyword but doing this looks at every word entered, if possible I want it to search for all keywords in any order so that the results page shows the most relevant results.

I search for “C4 envelope” and it returns 728 results with some results only having ‘C4’ in an others having ‘envelope’ in and I want it to only search for items containing both C4 and envelope.

Thank you for any help that you can offer.

Sorry for being so bad at explaining, here is my code for the search box:

<form name=“searchform” method=“get” action=“<?php echo url_for(“products/searchProduct”,true);?>” style=“margin-bottom:0px;”>
<span id=“searchCat”>
<select name=“search” id=“search”>

        	      &lt;option value="All" &lt;?php echo ($id=="All")?"selected":"";?&gt;&gt;Everything&lt;/option&gt;
        	      &lt;?php foreach($categoryArr as $key=&gt;$value) { ?&gt;
				  &lt;option value="&lt;?php echo $key;?&gt;" &lt;?php echo ($id==$key)?"selected":"";?&gt;&gt;&lt;?php echo $value;?&gt;&lt;/option&gt;
				  &lt;?php } ?&gt;
        	    &lt;span class="selectRequiredMsg"&gt;Please select an item.&lt;/span&gt;&lt;/span&gt;
				&lt;span id="searchfield"&gt;
              &lt;input type="text" placeholder="Search here..." name="searchfield" id="searchfield" value="&lt;?php echo ($searchTxt=='All')?"":$searchTxt;?&gt;"/&gt;
                  &lt;input name="searchWith" type="radio" value="exact" &lt;?php echo ($searchWith=='exact')?'checked':'';?&gt; /&gt;
                  Search as Phrase&lt;/label&gt;
                  &lt;input name="searchWith" type="radio" value="like" &lt;?php echo ($searchWith=='like')?'checked':'';?&gt; /&gt;
                  Search as Keywords&lt;/label&gt;
              &lt;span&gt; &lt;span class="textfieldRequiredMsg"&gt;A value is required.&lt;/span&gt;
              &lt;input type="submit" value="Search" id="searchbutt" name="searchbutt"/&gt;