display: flex;　を使用します。

.waku {
	padding: 0 15px 0 15px;
	width: 400px;
	height: 150px;
	border: solid red 1px;

	display: flex;
	justify-content: center;
	align-items: center;
	text-align:  center;
}
.elem {
	flex: 1;
}

デモ : https://pgmemo.tokyo/livedemo/css_flex_vertical_center/css_flex_vertical_center.html