The following snippet of Bootstrap code can be used to effectively support more than 12 cols within a parent row - in this case 16 columns.
The technique used here is to first divide the parent row into 4 3-col blocks.
Each of these 3-col blocks are further divided into 4 3-col blocks.
This result is 16 columns supported in the parent row.
<div class="container-fluid">
<div class="row">
<div class="col-md-3 col-sm-3 col-xs-6">
<div class="row">
<div class="col-md-3">
<h1>1 </h1></div>
<div class="col-md-3">
<h1>2 </h1></div>
<div class="col-md-3">
<h1>3 </h1></div>
<div class="col-md-3">
<h1>4 </h1></div>
</div>
</div>
<div class="col-md-3 col-sm-3 col-xs-6">
<div class="row">
<div class="col-md-3">
<h1>5 </h1></div>
<div class="col-md-3">
<h1>6 </h1></div>
<div class="col-md-3">
<h1>7 </h1></div>
<div class="col-md-3">
<h1>8 </h1></div>
</div>
</div>
<div class="col-md-3 col-sm-3 col-xs-6">
<div class="row">
<div class="col-md-3">
<h1>9 </h1></div>
<div class="col-md-3">
<h1>10 </h1></div>
<div class="col-md-3">
<h1>11 </h1></div>
<div class="col-md-3">
<h1>12 </h1></div>
</div>
</div>
<div class="col-md-3 col-sm-3 col-xs-6">
<div class="row">
<div class="col-md-3">
<h1>13 </h1></div>
<div class="col-md-3">
<h1>14 </h1></div>
<div class="col-md-3">
<h1>15 </h1></div>
<div class="col-md-3">
<h1>16 </h1></div>
</div>
</div>
</div>
</div>