How to collect data which exists centre or border of the cluster?
You can use numpy.where documentation can be fouind here :
https://docs.scipy.org/doc/numpy-1.10.1/reference/generated/numpy.where.html

You can define a function to extract your data ID somthing like this 

def ClusterIndicesNumpy(clustNum, labels_array): 
    return np.where(labels == cluster)[0]


To get samples from cluster 3 for example:

ClusterIndicesNumpy(3, km.labels_)